[DerXL]

Throwing away the kit may seem the best option, but I've noticed that Tamiya putty tends to get weaker when it's been soaked in brake fluid.
At least, that's what happened when I put my F430 body into the brake fluid. Areas that had been puttied had to be done again, because the putty had crumbled/rubbed off in places...

Before throwing away anything you might try to put the body into some DOT3 brake fluid and see if the putty gets weak/brittle enough to be scrubbed off...